The present invention relates to a system and method for assessing knee movement, and, more particularly, the range-of-motion in a knee joint, for example, as part of post-operative physical therapy.
Knee-related injuries are one of the most common injuries in sports. Many knee injuries result in a ruptured or torn anterior cruciate ligament (ACL), one of the four major ligaments of the knee. Injury to the ACL is often remedied by reconstructive surgery, followed by several months of physical therapy and rehabilitation. In order to track changes in the range-of-motion of the knee, a goniometer is often used to directly measure the angle between the lower and upper leg when in flexion. A goniometer is a plastic or metal tool with two arms, usually no longer than twelve inches, with at least one of the arms mounted for rotation relative to the other arm about a central axis. This central axis is aligned with the axis of rotation of the knee, and the arms are aligned with the greater trochanter of the femur and the lateral malleolus of the fibula in order to take a measurement using a scale on a central body portion of the goniometer.
One of the significant problems with a typical goniometer is the dependence on accurately positioning the central axis and the arms of the goniometer in relation to the patient's knee. Exacerbating this issue is the desire to take a measurement quickly so that the patient can return their leg to a relaxed position. Some studies suggest that these errors can be anywhere between 5 and 10 degrees when taking repeated measurements. Furthermore, a typical goniometer can only be used in a clinical setting with the assistance of a therapist.
Thus, there remains a need for improved systems and methods for assessing knee movement.